This invention relates in general to the manufacture of vehicle wheels and in particular to a device and method for deburring the ends of vehicle wheel holes.
Vehicle wheels include an annular wheel rim that supports a pneumatic tire. A wheel disc formed having a pleasing esthetic shape extends across the outboard end of the wheel rim. The wheel disc usually includes a central hub supported within the rim by a plurality of radially extending spokes. Apertures formed through the wheel hub allow attachment of the wheel to an end of a vehicle axle. Additionally, an aperture formed through a sidewall of the outboard end of the wheel receives a valve stem that is used to inflate the tire mounted upon the wheel rim.
Light weight vehicle wheels cast from alloys of aluminum, magnesium and titanium have become increasingly popular. Such wheels may be cast as one piece upon an automated casting machine. The wheel castings are then finished on machining stations that typically perform multiple machining operations. Thus, the wheel rim is turned to a final shape on a wheel lathe which also can be used to face the outboard surface of the wheel disc. The apertures in the wheel hub and the valve stem hole are drilled while the wheel is mounted upon a wheel hole drilling station. Alternately, the wheels may be assembled from several components that are first machined to final dimensions. Regardless of the method used, the manufacture of vehicle wheels is highly automated.
Referring to the drawings, there is illustrated in FIG. 1 a flowchart for a known method 10 for drilling holes through a vehicle wheel hub. The method 10 begins in functional block 20 with provision of a machining station for drilling wheel holes. Typically, the machining station is a Computer Numerical Control (CNC) machining station. The machining station is used to drill and finish a plurality of holes in a vehicle wheel and typically includes an automated drill head carrying multiple tools, which are indexed into drilling position as needed. For example, one set of tools may be used to form a valve stem hole. The tools would include a drill bit for forming a hole through the wheel sidewall, a counterbore for enlarging a portion of the drilled hole and a countersink for finishing the end of the hole at the bottom of the counterbore. Additionally, the machining station includes a clamping mechanism that holds the wheel and is movable to orient the wheel relative to the drill head. The method 10 then proceeds to functional block 25.
In functional block 25, a wheel casting is mounted upon the machining station clamping mechanism with the outboard wheel surface facing the automated drill head. The method 10 then proceeds to functional block 30. In functional block 30, the wheel is positioned for machining. For machining a valve stem hole in the wheel, the clamping mechanism orients the wheel with the wheel axis forming an angle relative to the tool axis. For machining a lug hole, the wheel is oriented with the wheel axis parallel to the tool axis. Preferably, the positioning is controlled by a program stored within the CNC machine.
In functional block 35, the wheel is drilled, for example, the valve stem hole drill bit may be rotated and advanced to form a valve stem hole. Preferably, the drilling is controlled by programming the CNC machining station. The method 10 then proceeds to functional block 40.
In functional block 40, the tool(s) for machining the wheel are withdrawn. In the case of machining a valve stem hole, for example, the valve stem hole drill bit is retracted. Preferably, the withdrawal is controlled by programming the CNC machine. For a valve stem hole, the drill head is indexed to present another tool to the wheel surface and the operations in functional blocks 35 and 40 are repeated as needed to fully form the hole. Thus, the drill head is indexed to align a counterbore tool with the hole axis and the method proceeds to rotate and advance the counterbore tool to form the counterbore. Then the drill head is indexed to align a countesink with hole axis and the method proceeds to rotate and advance the countersink tool to countersink the end of the hole in the base of the counterbore. After each machining operation, the tool is withdrawn. Once a hole is completed, the method 10 proceeds to decision block 42.
In decision block 42, the method 10 determines whether all of the needed holes have been drilled in the wheel casting. If the drilling operations are not completed, the method transfers to functional block 44 where the drill head is indexed. The operation in functional block 44 is shown as being optional because the same drill may be used again where multiple holes need to be drilled, as in the cast of the lug holes. The method 10 then returns to functional block 30 where the wheel is repositioned for the next drilling operation. If, in decision block 42, the method 10 determines that all of the drilling operations are completed, the method transfers to functional block 45 where the wheel is removed from the machining station. The method 10 then proceeds to functional block 50.
In functional block 50, any burrs that were formed along the edges of the holes during the drilling operations are manually scraped from the edges of the holes by hand with a knife blade.
The known method 10 is susceptible to non-uniformity as the hand scraping technique may vary from person to person when deburring the holes, or even by a single person from time to time. Further, the known method 10 is susceptible to holes not being deburred due to human oversight. In addition, the known method 10 requires a significant number of work hours to manually debur the valve stem hole edge. Accordingly, it would be desirable to automate the deburring process. It is believed that such automation would increase the uniformity and the overall quality of the wheels while reducing the number of labor hours required to the manufacture each vehicle wheel.